It has for some time been normal practice to secure inflatable life rafts on ships and other vessels in such a manner that the deflated raft is retained within a container on the vessel and the container, in turn, is secured to the vessel by means of a mechanism which releases in response to the hydrostatic pressure which results when the vessel sinks. The container is held to the vessel not only by the hydrostatic release but also by a painter which is secured to the contained raft and, when fully extended and forcefully pulled from the container, actuates a gas cylinder to inflate the raft and burst open the container.
The painter secured to the raft must be sufficiently strong to secure the raft to the vessel despite high seas and winds. Experience has shown that the painter and its connection to the raft must be so strong that it can, in certain instances, actually pull the raft down with the sinking vessel so that, although completely and automatically released and opened, the raft would be unuseable and carried to the bottom in its inflated condition with the sinking vessel.
In order to overcome this problem the painters have in the past been made of a rope having a breaking strength less than the buoyant force of the inflated raft but greater than that necessary to actuate the gas cylinder and inflate the raft. The breaking strength of such a painter, of course, may vary with the size of the raft but in most instances the breaking strength is on the order of several hundred pounds and consequently, when it is desired to release the raft manually the painter cannot easily be separated from the vessel unless there is some tool available for cutting it.
Moreover, the use of a painter having a specific breaking strength is not always satisfactory since knots which may be formed in the painter either intentionally or unintentionally drastically reduce the breaking strength. In some instances the strength of a knotted painter may be so reduced that the painter breaks without actuating the raft inflation mechanism. While it is possible to overcome this difficulty by manually actuating the inflation mechanism, this is difficult once the raft container and the prospective raft occupant are in the water. It is, of course, even more difficult at night time since the container, unlike the inflated raft, does not ordinarily include a self-starting beacon light such that the prospective raft occupant may find the raft.